diff --git a/src/create-main-handler.ts b/src/create-main-handler.ts
index 25baeea..70b1413 100644
--- a/src/create-main-handler.ts
+++ b/src/create-main-handler.ts
@@ -261,6 +261,8 @@ export function createMainHandler(
             response.headers.set('timing-allow-origin', '*');
         }
 
+        response.headers.set('x-esm-target', buildTarget);
+
         if (willCache) {
             const cacheWriteSpan = tracer.startSpan('cache-write', {
                 attributes: { 'span.type': 'cache' },
diff --git a/src/utils.ts b/src/utils.ts
index 9586b28..356e176 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -74,6 +74,7 @@ const denyHeadersList = [
     'cf-cache-status',
     'cf-ray',
     'content-length',
+    'connection',
     'date',
     'host',
     'last-modified',